1. Field of the Invention
The present invention relates to a polarizing plate, a liquid crystal panel, and a liquid crystal display.
2. Description of Related Art
A liquid crystal display (LCD) is a device displaying letters and images using electrooptic properties of liquid crystal molecules. The LCD is widely used in mobile phones, notebook PCs, liquid crystal display TVs, and the like.
A liquid crystal cell used for an LCD is normally used in a state where a polarizing plate is arranged on the one side thereof or polarizing plates are arranged on the both sides thereof. An example of the structure of the liquid crystal cell is shown in a schematic cross sectional view of FIG. 4. As shown in FIG. 4, in a liquid crystal cell 41, spacers 412 are arranged between a pair of substrates 411. A space is formed between the pair of substrates 411 with the spacers 412. In the space, a liquid crystal layer 413 is interposed between the pair of substrates 411. On one of the substrates of such a liquid crystal cell, for example, a switching element (e.g. TFT), a scanning line, and a signaling line are provided. The switching element controls electrooptic properties of liquid crystal molecules, the scanning line sends a gate signal to the switching element, and the signaling line sends a source signal to the switching element.
One of the properties required for a liquid crystal display is less occurrence of light leak at the time of a black display. As a drive mode of a liquid crystal cell for an LCD that is superior in this property, a vertical alignment (VA) mode is known (for example, see JP2004-46065 A). This VA mode liquid crystal cell has an alignment in which liquid crystal molecules are substantially perpendicular to the surface of the substrate in a state of unactuated. Therefore, light passes through a liquid crystal layer with very little change in a polarization plane thereof. Thus, the VA mode liquid crystal cell less likely causes a light leak in a state of unactuated, and the liquid crystal cell can provide an almost perfect black display.
However, as definition of LCDs (e.g. liquid crystal display TVs) is increasing in these years, black brightness in a plane of a liquid crystal panel is required to be reduced. As the black brightness decreases, if even just a little bit of light is leaked from a polarizing plate, a brightness irregularity may easily become noticeable. Therefore, leak of even just a little bit of light from the polarizing plate becomes a problem.